In the surgical repair of soft tissue, such as, for example, the surgical reattachment of ligaments to bone or the attachment of tendon to muscle, it is known to use multi-part devices to surgically fasten the soft tissues to be repaired to the bone so as to avoid the use of knots. Suture knots are disadvantageous because they can be difficult to effect in tight spaces, they may not be uniformly tensioned and thus may slip or bind, and they can cause pressure on, or trauma to, surrounding tissue.
U.S. Pat. No. 5,593,425 to Bonutti et al. discloses surgical suture fastening devices which are assembled using a heat bondable material. The '425 patent teaches that a portion of a suture thread is inserted into an opening in a retainer formed of a plastic material having a melting point which is lower than the melting point of the suture material. At least one portion of the retainer is heated to its melting point. The plastic material of the retainer flows around the suture thread and creates a bond with the suture thread as the molten plastic material of the retainer cools below its melting point.
One disadvantage of the device disclosed in the '425 patent is that the surgeon must maintain tension on the retainer while simultaneously heat bonding the retainer to the suture, a sometimes difficult procedure. Another disadvantage of the Bonutti et al. device is that because the material of the retainer melts over the suture strands to encase them, instead of the suture material itself melting and bonding to itself, it may be difficult to control the geometry of the bond and/or the melting of the retainer and sutures, resulting in non-uniform coverage of the sutures by the melted material which flows around it.
It would therefore be an advantage to provide a suture fastening device that not only holds the strands of a suture thread together in preparation for bonding, but also effects melting of the suture strands within the device so that the sutures themselves are joined together and are not merely encased in a retainer which has been melted and cooled around them.